president obama expressed his thanks from the white house. >> we owe a tremendous debt of gratitude to all our outstanding law enforcement professionals. >> reporter: the fbi marked his page, captured, and people gathered for a candle light vigil near the finish line of the marathon. in addition to a motive. investigators will be looking to answer if these two brothers were working alone or part of a larger terror group. we can tell you that three additional suspects have been taken into custody. it happened in new bedford, which is an hour away from watertown where this all played out. back to you. >> now the man hunt ended about 27 hours after the fbi released the suspect's photos. here's a closer look at the night of chaos that led up to the capture. >> the chaos began late last night, police called to a shooting on the m.i.t. campus. university police officer, sean collier was ambushed and killed. at 11:30 boston time, the brothers carjacked a man a few blocks away in cambridge. they told the driver they were the marathon bombers. a half hour later, they released the man unharmed w